The present application is directed to a method for laminating a plastic web onto the surface of an extruded plastic substrate. The plastic web may be a facade strip having a textured appearance and the extruded plastic substrate may be cut into segments after lamination for use in making prefabricated window systems.
An example of a prior art window system having extruded members will now be described with reference to FIG. 1. The window system includes a rectangular mainframe having a top frame portion 10, a bottom frame portion 12, and side frame portions 14 which connect portions 10 and 12. Frame portions 10-14 are made from extruded polyvinyl chloride (PVC) and all have the same cross-sectional configuration, except for features such as drainage channels which are fabricated after extrusion. Because they have the same cross-sectional configuration, frame portions 10-14 can be cut from a long substrate (not shown in FIG. 1) of extruded PVC. Frame portions 10-14 are joined at their corners by edge welds 16 and lateral welds 18 (which are also present on the side of the window system not shown in FIG. 1). The term "weld" in this context means that the corners have been joined by molten PVC which, when it cools, seals one frame portion to an adjacent frame portion along a smooth seam.
The side frame portions 14 provide channels for guiding a screen member 18 and for guiding window units 20 and 22 (which have sashes made from segments cut from an elongated substrate of extruded PVC, not illustrated). Window units 20 and 22 can be unlatched from the channels and tilted out for cleaning as shown. Since the top and bottom frame portions 10 and 12 have the same cross-sectional configuration as the side frame portions 14, channels are also present in top and bottom frame portions 10 and 12. An extruded PVC sill 24 is provided with resilient legs which permit sill 24 to be snap-connected to bottom frame portion 12. Balance mechanisms 25 (only one of which is shown) are mounted in the window guidance channels of side frame portions 14 to counterbalance the weight of window units 20 and 22. Window stops 26 (only two of which are shown) are snap-connected to side frame portions 14 to limit the movement of window units 20 and 22 so as to prevent possible damage to hardware mounted on the window units should they be slammed up or down.
FIG. 2 is a cross-sectional view of the bottom portion of the window system shown in FIG. 1, in its installed state. A rectangular opening in a wall 28 is framed by wooden strips 30 and interior trim 32. Nailing fins 34 are lodged into slots in frame portions 10-14 and are nailed into wall 28 to mount the window system in wall 28.
Further information about the construction of the window system can be found in U.S. application Ser. No. 06/929,303, filed Nov. 12th, 1986, the disclosure of which is incorporated herein by reference.
Since the process of extruding a plastic substrate leaves its own characteristically bland appearance to the surfaces of the substrate, in the past facade strips have been laminated to major visible surfaces of prefabricated plastic window systems to provide a wood-grain appearance. Such strips additionally increase the resistance of the window systems to weathering. However prior art techniques for laminating facade strips to extruded plastic substrates have not been entirely satisfactory. Facade strips laminated with prior art methods have had a tendency to become loose at the ends when segments are cut from a substrate and welded together. Furthermore, due to rough handling that may be encountered during transportation, storage, and installation of prefabricated window systems, the lateral edges of facade strips applied by prior art techniques may peel in places. Long years of exposure to the elements after installation, and possibly the prying hands of small children, may lead to further peeling.
In one prior art method for laminating a facade strip to an extruded plastic substrate, the substrate is moved through a cleaning station, where it is cleaned with soap suds. After drying, an adhesive-backed facade strip is pressed onto the member with rollers.